1. Field of the Invention
This invention relates particularly to marine riser joints where it is desired to provide a conductor or conductors through said joint in addition to the usual main bore through which drilling operations are performed. 2. The Prior Art
The point of connection of a riser pipe to the upper end of a well pipe at the ocean bottom is subject to high bending moments due to the shifting of the ocean currents and the movement of the drilling platform. Therefore, the riser joint at or near this point of connection has to be flexible to withstand these high bending moments and the prior art suggests the use of a ball joint to provide such flexibility. In many instances, hydraulically controlled equipment, such as a blowout preventer, is located below the joint and in such case, a conduit line or lines are required to conduct control fluid to said equipment.
In the prior art, it has been the practice to utilize multi-conduit lines or conductors which are located to extend around the exterior of the joint so as to bypass the same. The use of multi-conduit bypass lines is unsatisfactory because the lines are unprotected and subject to being broken, may interfere with guidelines, may inhibit access to the blowout preventer or other hydraulically-actuated equipment for maintenance purposes, and may interfere with sub-sea television viewing. In addition, the bypass lines or conductors undergo constant flexing as the joint parts move with the result that they are ruptured and have to be replaced several times a year at a substantial expense.